SIMPLE ESTIMATION METHODS FOR THE HELMHOLTZ-KOHLRAUSCH EFFECT

Foul-kinds of simple estimation equations are proposed for the Helmhol tz-Kohlrausch effect. Two of them can be used for luminous colors, and the other two for object colors, In each of luminous and object color s, the two estimation equations are given to each of the Variable-Achv omatic-Color (VAC) and the Variable-Chromatic-Color (VCC) methods. All the equations are similar in type to the Ware-Cowan equation, They gi ve the ratio between luminance (or metric lightness) of test color sti mulus and its equivalent luminance (or equivalent lightness) directly. Though their computations are simple, they can apply to various H-K e ffects including their adapting luminance dependency. The applicable f ields of the proposed equations are wider than chose of the Ware-Cowan equation, The proposed equations cart be applied to predict the H-K e ffect within the whole chromaticity gamut including spectral colors, s pectral luminosity, functions based on direct color matching front 0.0 1 Td to 100000 Td using the photopic and the scotopic spectral luminos ity, functions specified by CIE, equivalent lightness values of NCS co lors, and others. (C) 1997 John Wiley & Sons Inc.